<style>
    body {
        display: flex;
    }

        body iframe {
            flex-grow: 1;
            flex-shrink: 1;
        }

    ::-webkit-scrollbar {
        display: none;
    }
</style>
<script>async function attachFrame(frameId, url) {
        var frame = document.createElement('iframe');
        frame.src = url;
        frame.id = frameId;
        document.body.appendChild(frame);
        await new Promise(x => frame.onload = x);
        return 'kazakh';
    }</script>
<iframe src='./two-frames.html' name='2frames'></iframe>
<iframe src='./frame.html' name='aframe'></iframe>
